1. Field of the Invention
The present invention relates to a battery, a manufacturing method of battery, and a check method of electrolyte leakage.
2. Description of Related Art
As mobile appliances such as cellular phones, mobile-type personal computers, and the like are developed and practical use of pure electric vehicles, hybrid electric vehicles, and the like prevails, demands on not only primary batteries but also secondary batteries such as nickel hydride battery, lithium-ion battery, and the like has becomes larger. However, once electrolyte leakage occurs to those batteries, appliances have damages, which is problematic. Therefore, excellent sealing ability and electrolyte leakage proof performance have been required for batteries. Accordingly, accurate check method of electrolyte leakage has been required for manufacturing batteries and various check methods of electrolyte leakage have been proposed to meet such requests.
JP Unexamined Patent Publications Nos. 2001-297799 and 2002-246072 disclose check method of electrolyte leakage in which electrolyte leakage is judged by detecting fluorescence which electrolyte emits in response to irradiation of light which reacts on electrolyte and presence/absence of leakage is judged from a result of fluorescence detection.
JP Unexamined Patent Publication No. 2002-359010 discloses check method of electrolyte leakage in which fluorescent material is previously mixed in electrolyte and in case electrolyte leaks from a sealed portion after sealing, fluorescent material in electrolyte absorbs excitation energy and emits fluorescence, thereby to detect electrolyte leakage.
However, the check method disclosed in JP Unexamined Patent Publication No. 2001-297799 is effective to a battery of which electrolyte components include fluorescent material while not applicable to a battery of which electrolyte components do not include fluorescent material (solution-type battery such as nickel hydride battery, for example). Furthermore, since fluorescent material must be selected when composing electrolyte, composition of electrolyte is sometimes restricted.
In JP Unexamined Patent Publication No. 2002-246072, fluorescent material is previously mixed in electrolyte. However, when fluorescent material is mixed in electrolyte, fluorescent material reacts on other components of electrolyte and gets decomposed in a battery, whereby battery performance deteriorates considerably.